There has been suggested a device which assists a user in walking by applying a torque around a leg joint (hip joint, knee joint, or ankle joint) to a user's body (for example, see Japanese Patent Laid-Open No. 2003-135543). In addition, there has been suggested a system which controls the walking assist device in such a way as to add autonomy to the walking assist rhythm of the walking assist device while following changes in the user's locomotion rhythm (for example, see Japanese Patent Laid-Open No. 2004-073649).